Control and Calibration Recipes for Photonic Integrated Circuits

Abstract

This paper presents the key ingredients and the best practices for implementing simple, effective and robust control and calibration procedures for arbitrary photonic integrated circuit (PIC) architectures. Three main features are presented and discussed: a technique to cancel out the effects of mutual crosstalk among thermal tuners, the exploitation of labelling to identify different optical signals, the use of input modulated signal to automatically reshape the frequency response of the device.Examples of application are then illustrated to show the validity and generality of the approach, namely a cross-bar interconnect matrix router, a variable bandwidth filter and third order coupled microring filter. Further, the automatic and dynamic generation of the lookup table of add/drop hitless filters operating on a dense wavelength division multiplexing grid is demonstrated. The lookup table achieved with the proposed approach can dynamically update itself to new conditions of the chip or new requirements of operation, such as variations in channel modulation format or perturbation induced by neighboring devices due to a change in their working point.

Polarization-transparent silicon photonic add-drop multiplexer with wideband hitless tuneability

“…Advantageously, the enabling innovation is not a specific technology process, since the device was fabricated in a commercial silicon foundry. We exploited instead new strategies for the design, calibration, tuning and control of the photonic integrated circuit, which can be ported to other circuits and optical functionalities [27]. We expect that, beyond the high performance of the presented device for specific applications, these results may contribute to change the perception of what can be done now with integrated photonics, opening the door to new ultracompact, low cost, low-power consumption, fully reconfigurable and programmable photonic devices [30].…”

Dithering‐based real‐time control of cascaded silicon photonic devices by means of non‐invasive detectors

“…This feature is very useful in case of devices that require more than one heater to be operated, like MZIs, or in cascaded structures where many actuators affect the output optical power, like arrays of coupled microring resonators. In these situations, operating by only looking at the average output power requires complex techniques to take into account thermal crosstalk effects and perform an effective tuning action [22].…”

Polarization-transparent silicon photonic add-drop multiplexer with wideband hitless tuneability

“…1e), as measured by the power suppression at a photodiode coupled to the Drop port (black curve). Once the filter is disconnected from the bus waveguide, the final wavelength (1550 nm) can be selected by driving the MRRs heaters according to a pre-calibrated look-up table [27]. High isolation enables to perform the MRR resonance detuning with no effects on the Through port transmission of the filter across the entire wavelength range (1520 nm -1580 nm).…”